The present invention relates to a portable image display device for printed materials such as books, and more particularly to image display device and method having an open display function like a book as well as portability and suitable for displaying electronic sheet information.
An electronic apparatus for displaying electronic sheet information such as text or graphics on a liquid crystal display (LCD) device has been proposed. When the electronic sheet information is to be displayed on the liquid crystal display device, a currently available liquid crystal display device does not fully accomplish a role of books due to problems of resolution and portability thereof. This is because a limit in the present days LCD technology. However, in order to realize an image display device using the existing display system, it is most preferable to use the LCD which is superior to a CRT in the portability and the compactness.
A portable electronic apparatus which has two left and right open display screens which can be opened and closed in the same sense as a notebook and arranged closely to each other during the use has been proposed as an electronic apparatus having a book type display as disclosed in JP-A-3-217959, JP-A-4-355786 and JP-A-6-183389.
However, those prior art apparatus only suggest a so-called dual-screen independent display mode in which the dual open display screens are independently used and does not pay attention to a dual-screen integral mode and a display function such as magnification or edition.
In general, a print medium like a book has a resolution to permit recognition of a very fine character, and when book information such as cartoon is to be presented in the form of image, a resolution equivalent to 24 dots square per character which is a standard in the existing printers is required. When represented at 24 dots squares per character and assuming that each character has a size of 3 mm square, the resolution is approximately 8 dots/mm=approximately 203 dpi (dots/inch) to meet the requirement to display the book information. However, when the LCD is used as the display device to take place of the book, it is not sufficient compared to the media like books in terms of easiness to view the display screen and the resolution. Further, with the current technology of the LCD, it is difficult to attain the required resolution in view of the manufacturing and packaging technologies. The books have various sizes such as BUNKO size, SHINSHO size, magazine size and newspaper size and they have an advantage of compactness and portability so that they may be read in commuter trains and are easy to carry.